In onboard information equipment such as a car navigation system before factory shipment, a microcomputer working as the control center of the onboard information equipment is often connected to a PC (Personal Computer) serving as a diagnostic apparatus via a serial communication channel (serial communication interface unit) to inform the outside of the internal state of the microcomputer.
In the foregoing connecting configuration, the microcomputer receives a command from the PC, and carries out operation in accordance with the command. For example, when the input command intends a “memory dump”, the microcomputer outputs its dump list to the PC. Program developers analyze the dump list they get using the memory dump function, and carry out debug and the like of the program to develop the program and check its operation.
The foregoing memory dump function is sometimes used for checking on a mass production line after mass production following the program development. For example, it sometimes occurs that the operation environment of the microcomputer should be set in a specific operation mode (called “check mode” from now on) that the microcomputer does not use normally, such as disabling a display command to check the onboard information equipment to which a display monitor is not yet connected. Conventionally, such setting becomes possible by switching the operation mode of the onboard information equipment to the operation environment the microcomputer working as the control center does not use normally by inputting a command (such as “CHECK”) for switching to the check mode from the PC (see Patent Document 1 and Patent Document 2, for example).    Patent Document 1: Japanese Patent Laid-Open No. 62-78608/1987.    Patent Document 2: Japanese Patent Laid-Open No. 9-54766/1997.
According to the conventional arts including the techniques disclosed in the Patent Document 1 and Patent Document 2, to input a command to the equipment to be debugged such as the onboard information equipment, a comparatively large-scale expensive external apparatus must be connected as equipment like a PC. In addition, another problem arises of being unable to confirm as to whether the equipment to be debugged such as the onboard information equipment before shipment is currently set in the check mode, a special operation environment, or not externally.
The present invention is implemented to solve the foregoing problems. Therefore it is an object of the present invention to provide a debug system capable of changing, when setting the microcomputer, which works as the control center of the equipment to be debugged such as the onboard information equipment, in the operation environment the microcomputer does not use normally, the operation mode easily by inputting a command using a jig with a simple structure.